Personal computers are encroaching upon the area occupied by more traditional home entertainment systems. Rendering of audio and/or video content, such as movies, on personal computers is becoming increasingly popular. For example, personal computers can be equipped with DVD (digital versatile disk) drives that allow the computer to render movies from DVDs. By way of another example, personal computers can be equipped with television tuner expansion cards or other components that allow television signals to be received (e.g., via antenna or cable) by the computer for rendering. This encroachment is expected to continue, resulting in the replacement of traditional separate entertainment system components (e.g., VCR, DVD player, etc.) with a personal computer.
The creators of audio and/or video content, however, are very concerned with the security of personal computers. Traditional entertainment system components are “closed” boxes (they cannot be easily opened and components accessed, removed, modified, replaced, etc. while leaving the components operable) and thus relatively secure. Personal computers, in contrast, are “open” boxes—a portion of the housing can be removed and components (e.g., expansion cards) can be removed and replaced, new components can be installed, components (e.g., buses) can be accessed, etc. This creates a significant security risk for the content creators, because even though the personal computer designer/manufacturer may design the components of the computer to not perform any unauthorized tasks (e.g., inappropriate copying of descrambled content), there is often nothing preventing a malicious user from adding an additional expansion card (e.g., coupled to a bus of the computer) that does perform unauthorized tasks (e.g., copies the descrambled content from the bus for unauthorized distribution). In order for the content manufacturers to trust the security of open systems such as personal computers, a way to ensure the security of such content needs to be provided.
However, an additional factor that needs to be accounted for is the user response to any such security mechanisms. While most users understand, and accept, that they are not supposed to make unauthorized copies of content (e.g., copy movies for their friends, copy movies to the Internet, etc.), most users also do not want to be limited in their own enjoyment of movies and other premium content. For example, when people purchase a movie they may want to be able to watch it on different televisions in their house at different times, or take it to a friend's house and watch it there. Thus, it would be beneficial to provide a way to ensure the security of such content while at the same time not significantly interfering with a user's ability to enjoy the content he or she legitimately acquires.
The invention described below addresses these disadvantages, associating content with households using smart cards.